In the leaching of copper-containing ores (including copper-containing sulfidic ores such as chalcopyrite and/or enargite or other copper-containing sulfide minerals), the particle size of the ores is typically reduced from run-of-mine size, for example by crushing and grinding operations, to allow processing via heap leaching, vat leaching or reactor leaching options.
These leaching processes involve the application of an acid and an oxidant to dissolve copper into solution. Copper is subsequently recovered from the acidic solution by a range of recovery options including solvent extraction and electrowinning (SX/EW), cementation onto more active metals such as iron, hydrogen reduction, and direct electrowinning. The acidic solution is regenerated and recycled to leach more copper from the ores. Leaching may be assisted by the use of microorganisms.
Generally, leaching may provide lower metal recoveries than other process options for recovering copper from sulfidic ores, such as milling and flotation, that produce copper-containing concentrates that are then smelted to produce copper metal.
It is known that it is difficult to leach more than 20-40 wt. % of the total copper from chalcopyrite by heap leaching. The low copper recovery is often thought to be associated with the formation of a passive film on the surface of the chalcopyrite that may be composed of degradation products from the dissolution reaction.
The present invention was made in research and development work by a Group company of the applicant.
The present invention makes it possible to achieve higher recoveries of copper from copper-containing minerals in ores via an enhanced leaching mechanism.
The above description is not to be taken as an admission of the common general knowledge in Australia or elsewhere.